I read your comments and your grasp of the English language is nice. Your uni would not have given you an offer if they thought you wouldn't be able to communicate properly. You're doing great.
Also, if you want to improve, missing classes won't help you . It'll have the opposite effect. You need to be in an immersive environment where everything depends on the language. Going to classes and interacting with other English speakers will teach you new things, and push you to improve. Staying alone will not. Rather, your grasp of the language will deteriorate.